The objective of this study was to assess alterations in nutritional indices of Agrotis ipsilon larvae (fourth, fifth, and sixth instars) when fed Solanum tuberosum (potato) leaves, compared to those fed Ricinus communis (castor bean) leaves as a control diet. The results indicated that the consumption index (CI) was increased in 4th, 5th and 6th instar larvae fed on potato leaves on all days except the 2nd day of 5th instar larvae compared with castor leaves. However, relative growth rate (RGR) was decreased in fourth, fifth, and sixth instars larvae fed on potato leaves on all days except the 2nd day of 4th instar larvae compared with castor leaves.In general the efficiency of conversion of ingested food to biomass (ECI) was decreased in fourth, fifth, and sixth instars instar larvae fed on potato leaves on all days except the 2nd day of 4th, 5th& 6th instars compared with castor bean leaves. Also, the efficiency of conversion of digested food to biomass (ECD) was increased in fourth, fifth, and sixth instars nstar larvae fed on potato leaves compared with castor bean leaves. All of these results point to the difference in food utilization leading to difference in nutritional indices. As well as, the 4th instar larvae treated with magnetic and non-magnetic Zn elements and clove oil, the results cleared the effectiveness of unmagnetized Zn element rather than the other tested materials. This means that the magnetism decreased the efficiency of Zn element and clove oil when applied to A. ipsilon larvae.